The remarkable property of graphene to exhibit \(\sigma _{min}\sim e^2/h\)  even at vanishing charge density has been the subject of several experimental and theoretical investigations  [1]}, [2]}, [3]}, [4]}, [5]}. In a high mobility sample, a \(T\) -dependence is only expected for \(k_B T > \epsilon _F = \hbar v_F k_F = \hbar v_F\sqrt{\pi C_g(V_g-V_{NP})/e}\)  [6]}, [7]}, when \(V_g \rightarrow V_{NP}\) . However, in a realistic sample charged impurities  [8]}, [9]}, [3]}, [11]} or structural disorder  [12]} break up the carrier system into puddles of electrons and holes for \(V_g \rightarrow V_{NP}\) . As a result, the combined (electron plus hole) carrier density in "dirty" graphene never drops below a value \(\tilde{n}\)  , referred to as inhomogenity density (Fig. 2, Inset).
